Shaft-cylinder assembly for high temperature operation

ABSTRACT

The present invention provides a shaft-cylinder assembly for high-temperature operation comprising a dynamic sealing member having a helical coiled seal ring structure configured to be in contact with the shaft for providing dynamic sealing function; and a cylindrical cooling jacket positioned between the dynamic sealing member and the cylinder, and configured to circumferentially surround the dynamic sealing member and be circumferentially surrounded by the cylinder; wherein the cooling jacket includes one or more cooling channels, each of the one or more cooling channels is configured to circulate a cooling fluid for moving heat away from the dynamic sealing member.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is related to the U.S. patent application Ser. No.13/405,239 filed Feb. 25, 2012 and a divisional application of the U.S.patent application Ser. No. 16/297,653 filed Mar. 9, 2019; thedisclosure of which are incorporated herein by reference in theirentireties.

COPYRIGHT NOTICE

A portion of the disclosure of this patent document contains material,which is subject to copyright protection. The copyright owner has noobjection to the facsimile reproduction by anyone of the patent documentor the patent disclosure, as it appears in the Patent Office patent fileor records, but otherwise reserves all copyright rights whatsoever.

FIELD OF THE INVENTION

The present disclosure relates generally to shaft-cylinder sealingtechnology and more specifically relates to sealing technology in ahigh-speed shaft-cylinder assembly working at high temperatureenvironment.

BACKGROUND OF THE INVENTION

High-speed shaft-cylinder has been applied in various applications andequipment such as internal combustion engines, reciprocating pumps, gascompressors, and other similar assemblies wherein a rotary shaft or apiston shaft is the moving component contained by a cylinder and is madegas or fluid tight by seal rings.

The working temperature in some applications, such as internalcombustion reciprocating engine, may reaches up to 1500 to 2000° C. Thetransient temperature at location between the seal and the shaft mayeven be higher due to the frictional energy induced by high speedmovement. The extremely high temperature environment may cause failureof cylinder materials and oxidation of lubricating oil which result inshaft seizure. Furthermore, temperature variation over the engine maylead to a distortion of the engine components due to the thermalstresses. Cooling systems for internal combustion engines have beenproposed, for example, in U.S. Pat. No. 4,539,942 wherein two coolingjackets with cooling fluid passages are configured on a cylinder headand cylinder block in an internal engine. However, such coolingconfiguration cannot effectively move the transient heat from thelocation between the seals and the shaft.

On the other hand, various sealing techniques have been proposed forhigh-speed operation. For example, brush seals basically formed by amultitude of flexible fine steel bristles tightly clamped between twoplates have been used in a variety of high-speed rotating equipment.However, such type of seals may subject to leakage problem owning topressure-stiffening, hysteresis or other undesired seal behavior. Theleakage problem might be more serious in engines designed to haveslightly barrel shaped cylinders which are for compensating thedifference in severity of the scratching, and hence the different rateof erosion of the cylinder wall as a consequence.

SUMMARY OF THE INVENTION

It is an objective of the present invention to provide a shaft-cylinderassembly for high temperature operation, comprising a coolingconfiguration which can effectively move the transient heat from thelocation between the seals and the shaft such that distortion of enginecomponents due to the thermal stresses caused by the temperaturevariation may be eliminated. It is a further objective of the presentinvention to provide shaft-cylinder assembly with lesser number ofcomponents, improved durability, reduced power loss due to reducedshaft-cylinder friction, and significantly reduced leakage.

In accordance with one aspect of the present invention, theshaft-cylinder assembly comprises: a cylinder; a shaft configured formoving in and along the cylinder; a dynamic sealing member configured tobe in contact with the shaft for providing dynamic sealing function; anda cylindrical cooling jacket positioned between the dynamic sealingmember and the cylinder, and configured to circumferentially surroundthe dynamic sealing member and be circumferentially surrounded by thecylinder; wherein the cooling jacket includes one or more coolingchannels, each of the one or more cooling channels is configured tocirculate a cooling fluid for moving heat away from the dynamic sealingmember.

Alternatively, the shaft-cylinder assembly for high-temperatureoperation comprises a pair of first and second dynamic sealing membersconfigured to be in contact with the shaft for providing dynamic sealingfunction; and a cylindrical cooling jacket configured tocircumferentially surround the dynamic sealing members such that acavity is defined between the dynamic sealing members inside the coolingjacket; wherein the cooling jacket comprises one or more inflow coolingchannels and one or more outflow cooling channels configured tocommunicating with the cavity and circulating a cooling fluid throughthe cavity for moving heat away from the dynamic sealing members.

In accordance to another aspect of the present invention, theshaft-cylinder assembly further comprises one or more coiled felt seals(CFS) having a helical coiled seal ring structure which allows the CFSto contract when the shaft is travelling towards the upper end or lowerend of the cylinder and dilate when the shaft end is travelling throughthe middle section of cylinder. Therefore, the tight contact between theCFS and the cylinder interior wall can be sustained during the up-downstrokes of the shaft in the cylinder and leakage can be reduced to zeroor close to zero.

BRIEF DESCRIPTION OF DRAWINGS

Embodiments of the invention are described in more detail hereinafterwith reference to the drawings, in which:

FIG. 1 depicts a sectional view of a shaft-cylinder assembly for inaccordance with one embodiment of the present invention;

FIG. 2 depicts a sectional view of a shaft-cylinder assembly for inaccordance with another embodiment of the present invention;

FIG. 3 shows a CFS in accordance with one embodiment of the presentinvention;

FIG. 4 shows a partial cutaway view of the CFS in accordance with oneembodiment of the present invention;

FIG. 5A shows a cylinder seal ring in accordance with one embodiment ofthe present invention;

FIG. 5B shows a displacement absorption ring in accordance with oneembodiment of the present invention;

FIG. 5C shows a shaft seal ring in accordance with one embodiment of thepresent invention;

FIG. 6 shows a C-shaped basic source ring in accordance to oneembodiment of the present invention; and

FIG. 7 shows a method of progressive joining of two C-shaped basicsource rings in accordance to one embodiment of the present invention.

DETAILED DESCRIPTION

Hereinafter, embodiments of the present invention will be described withreference to the figures. It should be noted that the embodimentsdescribed herein are not intended to limit the invention in accordancewith the claims, and it is to be understood that each of the elementsand combinations thereof described with respect to the embodiments arenot strictly necessary to implement the aspects of the presentinvention. Additionally, well-known elements of the disclosure will notbe described in detail or will be omitted so as not to obscure therelevant details of the disclosure.

FIG. 1 depict a sectional view of a cylinder assembly 1 in accordancewith one embodiment of the present invention. As show in FIG. 1, thecylinder assembly comprises a cylinder 101; a shaft 102 configured formoving in and along the cylinder 101; a dynamic sealing member 103configured to be in contact with the shaft 102 for providing dynamicsealing function; a compression ring 104 engaged with a compressionspring 105 configured for providing a pressing force on the dynamicsealing member 103 to keep the dynamic sealing member intimately incontact with the cylinder 101; a pair of first and second holding rings106 a and 106 b for holding the dynamic sealing member 103 and thecompression ring 104 inside the cooling jacket.

The cylinder assembly 1 may further comprise a cylindrical coolingjacket 107 positioned between the dynamic sealing member 103 and thecylinder 101. The cylindrical cooling jacket 107 is circumferentiallysurrounded by the cylinder 101 and in turn circumferentially surroundsthe dynamic sealing member 103 and the compression ring 104. In someembodiments, the cooling jacket 107 may be configured tocircumferentially surround the dynamic sealing member 103 only. Thecooling jacket 107 may include one or more cooling channels 108, each ofthe cooling channels is configured for circulating of a cooling fluid,such as water, for moving heat away from the dynamic sealing member 103.Each of the cooling channels 108 may have an inlet 109 configured forreceiving the cooling fluid and an outlet 110 configured for releasingthe cooling fluid.

In accordance to various embodiments of the present invention, the inlet109 and outlet 110 of the cooling channels 108 may be coupled to acirculation pump (not shown). The circulation pump may be driven by apulley and belt from the crankshaft to drive heated fluid out from theoutlet 110 to a heat exchanger, such as a radiator. The fluid is cooledin the radiator by the process of radiation. The cooled fluid thenreturns to the inlet 109 and flows back into the channel 108 again.

The cylindrical cooling jacket 107 may further comprise a pair of firstand second snap ring grooves 111 a and 111 b formed on its interior walland configured for engaging respectively with a pair of first and secondsnap rings 112 a and 112 b which are fastened to the pair of first andsecond holding rings 106 a and 106 b respectively for fixing the dynamicsealing member 103 and the compression ring 104 inside the coolingjacket 107.

In accordance to various embodiments of the present invention, thecooling jacket 107 may have an outer diameter slightly smaller thaninner diameter of the cylinder 101 such that it is not in contact withthe cylinder 101. The cylinder assembly may further comprise a staticsealing ring 113 between the cooling jacket 107 and the cylinder 101 forproviding sealing function. The static sealing ring 113 may have aninner diameter slightly smaller than the cooling jacket outer diameterso that it can encircle tightly around the cooling jacket 107 and sealit, whilst its outer diameter is slightly bigger than the cylinder innerdiameter so that it pushes against interior wall of the cylinder 101from all directions to seal it. In some embodiments, the cooling jacket107 may have a ring groove 114 circumferentially formed on its outerwall for holding the static sealing ring on a fixed position around thecooling jacket 107.

FIG. 2 depict a sectional view of a cylinder assembly 2 in accordancewith another embodiment of the present invention. As show in FIG. 2, thecylinder assembly 2 comprises a cylinder 201; a shaft 202 configured formoving in and along the cylinder 201; a pair of first and second dynamicsealing members 203 a and 203 b configured to be in contact with theshaft 202 for providing dynamic sealing function.

The cylinder assembly 2 may further comprise a cylindrical coolingjacket 207 configured to circumferentially surround the dynamic sealingmembers 203 a, 203 b such that a cavity 220 is defined between thedynamic sealing members 203 a, 203 b inside the cooling jacket 207. Thecooling jacket 207 may include one or more inflow cooling channels 208 aand one or more outflow cooling channels 208 b configured tocommunicating with the cavity 220 and circulating a cooling fluid, suchas water, through the cavity 220 for moving heat away from the dynamicsealing members 203 a, 203 b. Each of the inflow cooling channels 208 amay have an inlet 209 configured for directing the cooling fluid intothe cavity 220 and each of the outflow cooling channels 208 b may havean outlet 210 configured for directing the cooling fluid out from thecavity 220.

In accordance to various embodiments of the present invention, the inlet209 and outlet 210 may be coupled to a circulation pump (not shown). Thecirculation pump may be driven by a pulley and belt from the crankshaftto drive the heated fluid out from the outlet 210 to a heat exchanger,such as a radiator. The fluid is cooled in the radiator by the processof radiation. The cooled fluid then returns to the inlet 209 and flowsback into the cavity 220 again.

The cylinder assembly 2 may further comprise a pair of first and secondcompression rings 204 a and 204 b engaged with a pair of compressionsprings 205 a and 205 b configured for providing pressing forces on thepair of first and second dynamic sealing members 203 a and 203 brespectively to keep the dynamic sealing members intimately in contactwith the cylinder 201.

The cylinder assembly 2 may further comprise a pair of first and secondholding rings 206 a and 206 b for holding the first dynamic sealingmember 203 a and the first compression ring 204 a inside the coolingjacket 207; and a pair of third and fourth holding rings 206 c and 206 dfor holding the second dynamic sealing member 203 b and the secondcompression ring 204 b inside the cooling jacket 207.

The cylindrical cooling jacket 207 may further comprise a pair of firstand second ring grooves 211 a and 211 b formed on its interior wall andconfigured for engaging respectively with a pair of first and secondsnap rings 212 a and 212 b which are fastened to the pair of first andsecond holding rings 206 a and 206 b respectively for fixing the firstdynamic sealing member 203 a and the first compression ring 204 a insidethe cooling jacket 207.

The cylindrical cooling jacket 207 may further comprise a pair of thirdand fourth ring grooves 211 c and 211 d formed on its interior wall andconfigured for engaging respectively with a pair of third and fourthsnap rings 212 c and 212 d which are fastened to the pair of third andfourth holding rings 206 c and 206 d respectively for fixing the seconddynamic sealing member 203 b and the second compression ring 204 ainside the cooling jacket 207.

In accordance to various embodiments of the present invention, thecooling jacket 207 may have an outer diameter slightly smaller thaninner diameter of the cylinder 201 such that it is not in contact withthe cylinder. The cylinder assembly may further comprise a staticsealing ring 213 between the cooling jacket 207 and the cylinder 201 forproviding sealing function. The static sealing ring 213 may have aninner diameter slightly smaller than the cooling jacket outer diameterso that it can encircle tightly around the cooling jacket 207 and sealit, whilst its outer diameter is slightly bigger than the cylinder innerdiameter so that it pushes against interior wall of the cylinder 201from all directions to seal it. In some embodiments, the cooling jacket207 may have a ring groove 214 circumferentially formed on its outerwall for holding the sealing ring on a fixed position around the coolingjacket 207.

In accordance to various embodiments of the present invention, thedynamic sealing members may be a coiled felt seal (CFS) formed byassembling a plurality of metal dynamic sealing rings which have ahelical coiled seal ring structure as disclosed in the PCT InternationalApplication No. PCT/CN2012/071634.

FIGS. 3 and 4 show an isometric view and a partial cutaway view,respectively, of a CFS 500 in accordance with one embodiment of thepresent invention. As shown in FIG. 4, the CFS 500 has three differentfunctioned layers: cylinder seal layer 501, displacement absorptionlayer 502 and shaft seal layer 503. The functional layers may be formedby groups of their corresponding basic source rings. FIGS. 5A-5C showsthree types of C-shaped basic source rings: cylinder seal rings 601 forforming the cylinder seal layer 601, displacement absorption rings 602for forming the displacement absorption layer 502 and shaft seal rings603 for forming the shaft seal layer 503, respectively.

The function of the cylinder seal layer 501 is for blocking the leakbetween inside diameter of the cylinder 1 and CFS 500. The correspondingcylinder seal rings 601 have outer diameter slightly bigger than thecylinder inner diameter so that they push against the cylinder interiorwall from all directions to seal it, whilst their inner diameter isbigger than the shaft diameter that they never touch the shaft surface.

The displacement absorption layer 502 is built between the cylinder seallayer 501 and the shaft seal layer 503 to absorb eccentric vibration ofthe shaft and also absorbs the dimensional change of the whole system bywearing along with use. The corresponding displacement absorption ringshave inner diameter bigger than the shaft diameter so they never touchthe shaft surface, whilst their outer diameter is smaller than thecylinder inner diameter so that they never touch the cylinder interiorwall.

The function of the shaft seal layer is blocking the leak betweenoutside diameter of the shaft 2 and CFS 500. The corresponding shaftseal rings 603 have inner diameter slightly smaller than shaft diameterso that they can encircle tightly around the shaft sealing block surfaceand seal it, whilst their outer diameter is sharing the same outerdiameter of the displacement absorption rings, which is smaller than thecylinder inner diameter such that they never touch the cylinder interiorwall.

The displacement absorption rings of the CFS allow big tolerance ofmisalignments in the shaft-cylinder assembly because the rings in thissection are movable in the latitudinal directions, swinging around toabsorb vibrations and lateral movements caused by the misalignmentsbetween the shaft and the cylinder under high speed up-down strokemotion. As such, the presence of the displacement absorption sectionring in the CFS also reduces the unwanted torque due to misalignmentamong the center of the shaft.

FIG. 6 shows a C-shaped basic source ring 700 which is a partial ringwith a pair of male dovetail 701 and female dovetail 702 in accordanceto one embodiment of the present invention. The C-shaped ring may bestamped out by press or fabricated by contour cutting process such aslaser cutting or wire cutting from sheet stock to have two faces inperfect parallel. As shown in FIG. 13, the C-shaped basic source ring700 is a partial ring that made to have a part of the ring cut away soas to make the partial rings be progressively joined by the maledovetail 701 and female dovetail 702 made on two ends of the partialring. The value of the cut away angle should be determined accordinglyalong with diameter.

FIG. 7 shows the method of progressive joining of two C-shaped basicsource rings 700 by the male dovetail 701 of first partial ring 700 andfemale dovetail 702 of next partial ring 700.

Because each C-shaped ring is only a partial circle, in order to provideeffective sealing function, a minimum of two shaft seal rings, a minimumnumber of two-cylinder seal rings and at least one displacementabsorption ring is needed to form a complete CFS.

The helical coiled seal ring structure of the CFS can assure perfectsealing performance. It allows the CFS to contract when the shaftsealing block is travelling towards the upper end or lower end of thecylinder and dilate when the shaft sealing block is travelling throughthe middle section of cylinder. Therefore, the tight contact between theCFS and the cylinder interior wall can be sustained during the up-downstrokes of the shaft in the cylinder and leakage can be reduced to zeroor close to zero.

The foregoing description of the present invention has been provided forthe purposes of illustration and description. It is not intended to beexhaustive or to limit the invention to the precise forms disclosed.Many modifications and variations will be apparent to the practitionerskilled in the art.

The embodiments were chosen and described in order to best explain theprinciples of the invention and its practical application, therebyenabling others skilled in the art to understand the invention forvarious embodiments and with various modifications that are suited tothe particular use contemplated. It is intended that the scope of theinvention be defined by the following claims and their equivalence.

What is claimed is:
 1. A shaft-cylinder assembly, comprising: acylinder; a shaft configured for moving in and along the cylinder; adynamic sealing member configured to be in contact with the shaft forproviding dynamic sealing function; and a cylindrical cooling jacketpositioned between the dynamic sealing member and the cylinder, andconfigured to circumferentially surround the dynamic sealing member andbe circumferentially surrounded by the cylinder; wherein the coolingjacket includes one or more cooling channels, each of the one or morecooling channels is configured to circulate a cooling fluid for movingheat away from the dynamic sealing member.
 2. The shaft-cylinderassembly of claim 1, wherein each of the one or more cooling channelshas an inlet configured for receiving the cooling fluid and an outletconfigured for releasing the cooling fluid.
 3. The shaft-cylinderassembly of claim 1, further comprising a compression ring engaged witha compression spring configured for providing a pressing force on thedynamic sealing member to keep the dynamic sealing member intimately incontact with the cylinder.
 4. The shaft-cylinder assembly of claim 4,further comprising a pair of first and second holding rings for holdingthe dynamic sealing member and the compression ring inside the coolingjacket.
 5. The shaft-cylinder assembly of claim 4, wherein thecylindrical cooling jacket comprises a pair of first and second snapring grooves formed on an interior wall of the cylindrical coolingjacket; wherein the first and second snap ring grooves are configuredfor engaging respectively with a pair of first and second snap ringswhich are fastened to the pair of first and second holding ringsrespectively for fixing the dynamic sealing member and the compressionring inside the cooling jacket.
 6. The shaft-cylinder assembly of claim1, further comprising a static sealing ring between the cooling jacketand the cylinder for providing sealing function; and wherein the coolingjacket has a ring groove circumferentially formed on an outer wall ofthe cooling jacket for holding the static sealing ring on a fixedposition around the cooling jacket.
 7. The shaft-cylinder assembly ofclaim 1, wherein the dynamic sealing member has a helical coiled sealring.